This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A026407 #10 Apr 10 2022 15:26:53 %S A026407 1,2,4,6,7,10,12,15,19,23,28,31,36,37,45,49,58,60,67,75,77,90,91,104, %T A026407 110,111,125,135,145,158,160,163,186,202,203,218,219,236,254,256,274, %U A026407 283,303,322,325,353,358,359,390,405,407,448,450,477,492,494,498,543,544,547,587,589 %N A026407 a(n) = greatest k such that s(j) > 0 for all j < k at end of stage n in forming A026409. %Y A026407 Cf. A026409. %K A026407 nonn %O A026407 1,2 %A A026407 _Clark Kimberling_ %E A026407 More terms from _Sean A. Irvine_, Sep 26 2019